fix: update edition in Cargo.toml from 2021 to 2024

Author: willpuckett

rmk/Cargo.toml

@@ -6,7 +6,7 @@ description = "Keyboard firmware written in Rust"
 homepage = "https://github.com/willpuckett/sessile"
 repository = "https://github.com/willpuckett/sessile"
 readme = "README.md"
-edition = "2021"
+edition = "2024"
 license = "MIT OR Apache-2.0"
 
 [dependencies]